Questions tagged [energy-conservation]
The law of conservation of energy, which states that the amount of energy in a system is constant. For questions about Earth's environment, see the climate-science tag instead.
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Does A Pivot Exert A Force
On a frictionless horizontal table, a uniform stick is pivoted at its middle, and a ball collides elastically with one end, as shown in Fig. 8.10. During the collision, what are all the quantities ...
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Why particle is certain to escape the conservative field when the mechanical energy is positive? [closed]
It is generally said that the particle is bound into the conservative field when the mechanical energy is negative and zero is the limiting case and the particle will escape the field when the ...
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Energy and momentum conservation for photon absorption [duplicate]
As an undergrad physics student, I am pondering on this question.
If an (2 level) atom absorbs a single resonant photon, the energy of electronic state increases by $\hbar \omega$. At the same time ...
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Where does the energy in a fundamental interaction come from?
When you have two electrons, they in the most likely possibility will exchange a photon, and it will cause them to repel each other. When they repel, their momentum increases, right? This momentum ...
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Find the tension in the string when the string is vertical [closed]
By using Work Energy Theorem, as well as Velocity of centre of mass, I succeeded in finding the velocities of both the ring as well as block. I noticed that there is going to be a vertical circular ...
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Is there a straightforward simplified proof of energy conservation from time translation symmetry?
Electric charge conservation is easily proven from electric potential gauge symmetry, as follows:
The potential energy of an electric charge is proportional to the electric potential at its location.
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Strogatz's condition on definition of energy
In, Nonlinear Dynamics And Chaos, 2nd edition page 160, by Steven H. Strogatz, he writes
Let’s be a bit more general and precise. Given a system $$\dot x =f(x),$$ a conserved quantity is a real-...
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Validity of $\mbox{d}H/\mbox{d}t=\partial H/\partial t$ for dissipative systems
It' well known that in Hamiltonian formalism one has
$$
\frac{\mbox{d}H}{\mbox{d}t} = \frac{\partial H}{\partial t}.\tag{*}
$$
One proof can be found here. Therefore, the total change of energy during ...
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Spring potential energy, conversion
I have a physics problem in my book, where a spring is compressed and a ball is laying in the end of the spring. When the spring is released the ball will reach a certain speed. In the solution it ...
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Does a rocket moving in a circle expel exhaust at a greater velocity?
Consider a rocket undergoing constant acceleration in a rectilinear path. Assuming the rocket is ideal (ignoring fuel mass and energy loss such as sound, radiation, vibration, etc.) a portion of the ...
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Why in two block system, both block tends to have same velocity at maximum potential energy when no external force is applied? [closed]
Consider a hemispherical bowl and a block placed inside it if the bowl is given velocity $v$ and given that there is no friction, the block will gain kinetic energy and then will rise to a maximum ...
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Energy Transfer and Work in Action-Reaction Forces [closed]
simple but confusing for me. I hope this question doesn't close or disappear. Questions continue to arise about work and energy.
Situation Description
A and B exert forces on each other and do work.
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Is it possible to lower the energy of the vacuum?
The energy of the vacuum is given by $$\sum_k \frac{1}{2}\hbar\omega_k.$$ However the frequency $\omega_k$ depends on the wavevector $k$ and some constants like the speed of light $c$, which in turn ...
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Is it possible there can be a non-Fourier model of string vibration? Is there an exact solution?
I am looking for a model of string vibration that does not assume the string is Fourier. Is there a Hamiltonian?
The equation of motion must be a function of length and tension, not time, and it must ...
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Do off-centre forces create additional energy?
When a force is applied to a rigid body at its centre of mass, it accelerates. Over time, that acceleration becomes velocity, which gives the body a certain amount of kinetic energy.
However, if that ...
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